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    <title>Document</title>
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            font-family: monospace;
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    <script>
        document.write("格式一：");
        document.write("<br><br>");
        for(var i=1;i<=9;i++){
            for(var j=1;j<=i;j++){
                document.write(i+"*"+j+"="+i*j+(i*j<10?"&nbsp;&nbsp;":"&nbsp;"));
            }
            document.write("<br>");
        }
        document.write("<br><br>")
        document.write("格式二：")
        document.write("<br><br>")
        for(var i=9;i>=1;i--){
            for(var j=1;j<=i;j++){
                document.write(i+"*"+j+"="+i*j+(i*j<10?"&nbsp;&nbsp;":"&nbsp;"));
        }
                document.write("<br>");
        }
        document.write("<br><br>")
        document.write("格式三：")
        document.write("<br><br>")
        for(var i=1;i<=9;i++){
            for(var j=1;j<=9-i;j++){
                document.write("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
            }
            for(var k=1;k<=i;k++){
                document.write(i+"*"+k+"="+i*k+(i*k<10?"&nbsp;&nbsp;":"&nbsp;"));

            }
            document.write("<br>");
        }
        document.write("<br><br>")
        document.write("格式四：")
        document.write("<br><br>")
        for(var i=9;i>=1;i--){
            for(var j=1;j<=9-i;j++){
                document.write("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;");
            }
            for(var k=i;k>=1;k--){
                document.write(i+"*"+k+"="+i*k+(i*k<10?"&nbsp;&nbsp;":"&nbsp;"));
            }
            document.write("<br>");
        }
    </script>
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